Several types of chairs are provided with reclining mechanisms. Certain reclining mechanisms in chairs include a base structure that allows the seat to slide forwards and backwards and cause inclination of the back part of the seat. Current locking mechanisms that are used to stop movement of the base structure and keep the seat base from sliding typically include nut and bolt type interfaces. However, this type of interface does not provide adequate locking capability for positioning of the seat. Bolt systems are typically not very performant and sometimes are subjected to problems after long periods of use.
Several different prior art mechanisms using spiral jaws as part of an adjustment mechanism in chairs, or other apparatuses, are known to the Applicant.
U.S. Pat. No. 6,135,524 (Faller et al.) discloses a frame structure (unrelated to a chair mechanism) using a spiral jaw clutch type system for the translational movement of a rod against a spring in order to adjust the configuration of a mechanism inside a structure.
US 2007/0170767 (Oberlaender et al.) teaches an adjustment mechanism for a surgical armrest using a spiral jaw clutch type system for the adjustment of a mechanism of the armrest.
U.S. Pat. No. 5,029,940 (Golynsky et al.) teaches a chair tilt and chair height control apparatus where the tilt control mechanism uses a spiral jaw clutch type system to control the adjustment of the tilting of a section of the chair.
Other mechanisms known to the Applicant include U.S. Pat. No. 3,936,091 (Rabinowitz); U.S. Pat. No. 4,540,148 (Jann); U.S. Pat. No. 4,728,072 (Mitchell); U.S. Pat. No. 6,719,372 (Glaspie et al.); and U.S. Pat. No. 7,611,201 (Moriyama et al.).
However, none of the prior art documents cited above discloses a spiral jaw clutch mechanism for locking and unlocking an adjustment system sliding along a slotted element and associated with the positioning of a chair seat.
Consequently, there is presently a need for a chair adjustment mechanism that uses a spiral jaw clutch to offer improved locking performance and operate reliably over a longer period of time.